Adjustable indicating structure on a measuring apparatus



April 19, 1949- G. LOWKRANTZ 2,467,899

- ADJUSTABLE INDICATING STRUCTURE ON A MEASURING APPARATUS Filed Oct. 24, 1945 GUNNE LOWKRAN Ti -INVENTOR.

%%J/ TTORN S Patented Apr. 19, 1949 INDICATINGR STRUCTURE; 01$ AZMEASJ RIN G GunnelLnwk a t mton, assisrwr t Iiink" Aviation" Devices," Inc;,- Bing lfamton, NiY-I; acorporationoiiNewiorle Application; Qctoberz 24, 1945,; Serial l\T.o.;62.1,21'7- 3. Claims: (c1. 116 12 My l invention. relates. to. means for accurately, determining the '..positi0n:.t.o'. a movablel member. and will: .be illustrated .lasait mayr be appliedjto a. sextant, However, it .will be ..appreciated,, rafter readingthe specification;andstudyingthe, draw-.

ings appended hereto that my c improved appae ratus may be, applied tagman y types: oi mechaa nism where it: is necessary, tor/accurately deter.

mine avaluewhichisrdependent-upon the angular or linear position of a member.

In order that the exact naturetofi my invention may be, better undenstood, reference issmade to the accompanying;- drawings l in; which, t

Fig; 1i indicates-r schematically the" essential partsot asextant. andqonerma ner n whichmyt invention may v-betusett therewith.

Fig. 2=is. a vcrossqsectional-evievsnitaken along: the-,-

hand- 74 areenlarged viewsof one .cof tthe; scales and associated/parts which :may be used:

with my nvention;

Referring toothe accompanying. drawings, the, numeral; I 2 .i designates, a. cornierrtionalsextant l casing; inwhichg'the-mainshaft .JA mayPbesuitahIy rotatablyy muntedt Afiixed upon theshafit this the, conventional.--index mirror. ltythisr index. mirror being the member whose position it 218'- desired.:tozjaccuratelygdetermine. It will be appreciated that the index mirror I6 may be moved by the observer-rhyga'rotatiorrofirthemain shaft H! in orderto bring the images of the bubble IBMof the-artificial horizon and celestial'jbody 21 The reflecting mirror into optical coincidence. 22 reflects thedmagerofitllehubblerwiztothe optical index mirror [6 throughthe collimating lens .23.";

The'index arm zl'is also .afilxedi to themain shait l4, for vrotation therewith and with the index mirrorltso thatthe'position of theindex arm; .24i-is atfiall'times dependentinpon thexposiei tion; of the index mirror I 6; ItT-owilibe notedith'at the lower end of the indexarm 24 carries an index mark 26.

The sextant casing ILis-provided with asuit ,v

Fixedly carried by, the frame 12.01' the sextantv is the .nut, 32 in. which thesscrews 3i4iis .rotatably carried; The -,,end Toffsc'rewV34 adjacent.scale.l2,8r f ri' e ly gag the .nub; vsefwhichi .is .iormed.

integraliwith'scale 2'83 About-toutjportion,3,8llis.

provided in. the, sextant casing. 12' at the -.oth'erm end jfof" scale '28.. and a 'compression .sprin'gJll 'li'sl. placed in. thisscutrout. portion, suitable ,guidi'as and.' supporting members.42 being-aifiXed,. to,the..sex=, tant frame I 2 fiand, 't'oithet endoi fsca1e-281in order-J toi'position spring 4.02; It willlbe.appreciatedj'thatio thfi sspring 4 B bears against the scale a 28;? at all times so, that the nub 3li always engages theadjar. cent endgof iscrew 3.4

fixedly; mountedgupon theouter endgot screw 3jis thjeinde'x, drum. which. in, theicase otpia. sextant is. graduated in minutes. of are from. zero c. through :1 T" suitable stationary index 4 6;l-is.. carriedjloy the. nut ,32; adjacent the drum M to! cooperate withv th'e graduationslthereuponu R'eierring now to Fig 3; it willibe seenlthat the. drum d4 is not graduated throughout v3601?. dz grees, but thatfa shortdistance is. present between, the eta and '60 "minute :graduationa. Fixedlyi carriedfby the drum 4!: at aHppinLISOHdegreest opposite the spacebetween. the-.55). andi6'0' minute. gradiiations, is therpinABJ Assh'own iniFigsa3l. and 4', a stop 50'is'fixedly carried by the sextant. casing I2. Whenever. thecdrum 4A. in figl. are rotated counterclockwise as. seenfrom the lower right :in 1371s., 3- untirth'e-cpin ABYJeneageswthe stop 1 1 t ndex .46]. is exactly .coincident, with the 60' minute graduation upon dfr'untd li O'n other ,hand,.sh0u1d the drum .441be rotated; clockwise from the position seen in Fig.,,31..-until=\thepin 48 iengages the other-side .oij'stop 5,0,1 itl ,Willif. be oappreciated-jlthatlthe drum. 44 mlllbemotatedl through. slightly lessnthanmone revolution. and; that the index,marki lfigwilliexactly coincide with he o. radua onupoh drum .44.". Itlwillitheree fore belapnreci t d hat the ,drum All cann rer be rotated through" 3,60ydegrees. a

In explanation it may be stated that .thel-lead of screw .34 and the graduations upondrum 4'4 are such that when ,..drum.. idtistrotatedt-through .7

sixty minutes .of graduations, the scale 2-8loshoulda move along the track 21 exactly the distance between two of the adjacent graduations thereupon. Thus in the instant illustrated case, for a given angular movement of drum 44, representative of a given number of minutes of arc, the scale 28 is moved along the track 2! the proper proportional amount of the distance between any two of the adjacent marks thereupon.

In the use of the previously disclosed measuring apparatus, after the observer has manipulated the conventional and well known controls of the sextant so that the index mirror [6 is positioned at the point whose value it is desired to ascertain, the position of the index mark 26 relative to the graduations along the scale 28 is ascertainedin the illustrated case 80 plus a fraction. The drum 44 is then rotated clockwise as seen from the left in Fig. 1 until the spring 40 has moved the index scale 28 to the left so that the index mark 26 upon the arm 24 is exactly opposite the 80 degree mark upon the index scale 26. The value of the index mark upon the drum 44 closest to the index 46 is then ascertained. The exact reading desired is then the whole number of degrees as shown by the relative positions of the index mark 26 and the scale 28- in the illustrated case Bil-plus the resultant reading obtained by reference to the index 46 and the drum 44-in the illustrated case about l5--or 80 degrees 15 minutes.

Inasmuch as the drum 44 can never be rotated through more than sixty minutes of graduations, it is impossible for the user of the instrument to secure an erroneous reading. It is only necessary that the operator rotate the drum 44 until the index mark 26 coincides exactly with one of the graduations upon the index scale 28. This reading is the number of degrees, and the number of minutes may be ascertained by noting the position of the drum 44 relative to the index 46. For initially adjusting the previously described apparatus, in the illustrated case the drum 44 is positioned so that the index 46 is opposite the zero mark on the drum. Index arm 24 is then moved until the index mark 26 is opposite the zero mark upon scale 28. The index mirror 16 is then fixed upon shaft [4 in the zero position. Thereafter the entire apparatus will always fun-ction properly so that the instant position of the index mirror [6 may be ascertained at any time. It is not necessary that the scale 28 and drum 44 be returned to any particular position after an observation is made and before a later observation is taken because the displacement of the scale 28 from its initial zero position is always shown by reference to the index 46 and the drum 44.

A magnifying glass, either carried manually or I afi'ixed upon the index arm 24 above the index mark 26 may be used to determine the exact coincidence of the index mark 26 with the graduations upon scale 28.

It will be appreciated by those skilled in the art that changes may be made in the disclosed embodiment of my invention without departing from the scope thereof, and further, that my invention may be useful when adapted for use upon other types of instruments and devices than that disclosed herein. All such changes and all such Variations in application are intended to be covered by the following claims.

I claim;

1. A measuring apparatus of the class described comprising, in combination with a movable member the position of which is to be determined, a first index mark movable with said movable member and a first graduated scale arranged for cooperation with said index mark and independently movable relative to the index mark, a second index mark and a second graduated scale arranged for cooperation with one another, one of said last two elements being movable relative to the other, and a micrometer drive between the movable one of said last two elements and the first graduated scale for moving the first graduated scale relative to the first index mark in response to the relative movements between the second index mark and the second scale.

2. In a sextant or similar instrument the combination of a movable member, a first index mark and a first graduated scale arranged for cooperation with said index mark, said index mark being movable with said movable member relative to said graduated scale and said graduated scale being independently movable relative to said index mark, a second index mark and a second graduated scale arranged for cooperation with one another, one of said last two elements being movable relative to the other, and a micrometer drive between the movable one of said last two elements and the first graduated scale for moving the first graduated scale relative to the first index mark in response to the relative movements between the second index mark and the second scale.

3. A measuring apparatus of the class described comprising, in combination with a movable member the position of which is to be determined, a first index means comprising an index mark and a graduated scale arranged for cooperation with one another, one of said last mentioned members being affixed to said mova-ble member and the other being independently movable, a second index means comprising an index mark and a graduated scale, one of said last two elements being movable relative to the other, and a micrometer drive between the movable one of said last two elements and the independently movable member of the first index means for moving the same in response to relative movements between the elements of the second index means.

GUNNE LOWKRANTZ.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED sTATEs PATENTS Number Name Date 552,751 Denison Jan. 7, 1896 751,647 Hutchins Feb. 9, 1904 891,621 Konig June 23, 1908 1,592,121 Moore July 13, 1926 2,364,764 Wilks Dec. 12, 1944 2,411,870 Chauret Dec.. 3, 1946 FOREIGN PATENTS Number Country Date 508,871 France Aug. 4, 1920 332,021 Germany Jan. 19, 1921 

